A technique is described which can be used to automatically classify Arctic
ambient noise data collected using an array of hydrophones suspended below the
ice. The technique is currently designed for analyzing low-frequency (5--60 Hz)
noise collected from the central Arctic pack ice. It is capable of
distinguishing between nearby or distant active pressure-ridging events, thermal
ice-cracking events, biological noise, cable strum, flow noise, and microseisms.
Different noise types are distinguished by the power spectra, cross spectral
matrices, noise directivity, and modal decomposition of the received sound. The
technique is designed to be used in a real-time system which can automatically
classify the dominant noise contained in the data over a specified time
interval. This technique is applied to data obtained in the Lincoln Sea over 5
days in April 1988 to show how the ambient noise characteristics change with
time during this period. Application of the algorithms produced a quantitative
classification of the noise type that was clearly recognized in displays of the
distinguishing measures.

Standards Committee S12 on Noise. Working group chairs will report on their
progress for the production of noise standards. The interaction with ISO/TC
43/SC1 and ISO/TC 94/SC12 activities will also be discussed, with reference to
the international standards under preparation. the Chairs of the respective U.S.
Technical Advisory Groups (H. E. von Gierke and E. H. Berger) will report on
current activities of these international Technical Subcommittees under ISO.
Scope of S12: Standards, specifications and terminology in the field of
acoustical noise pertaining to methods of measurement, evaluation and control;
including biological safety, tolerance and comfort and physical acoustics as
related to environmental and occupational noise.